Umaga pleased with defence
The New Zealanders won 24-16 in a physical encounter and were tested on a number of occasions out wide by the Argentinians.
"In past games we probably would have given up a lot more points than we did," said Umaga after the match.
"Our defence is something that we have been working hard on. We knew the Argentinian side would come and play.
"They chance their arm and they don't hold back. I thought we handled that well. They left some players behind, but we got to play the guys that front up and I thought our guys did that well."
Umaga also said his team took some time to adapt at the breakdowns.
"We got to adapt to the referee and he did say at the start that he will be strong in that area and he was.
"That is a learning curve for our guys. When it looks like we can hang in there and try to steal the ball back, we just have to let it go and trust our systems and get back into it.
"I think once we did that things turned around. Once we turned them around on defence they got a little bit frustrated. That is what good sides do.
"We still got a bit to learn, but we can take a lot of heart out of that," Umaga added.
The Blues will play the high-flying Chiefs in Hamilton in Round Six.
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